Agents and Intelligent Systems

Learn about the design, functions, and types of AI agents and discover how they are the building blocks for creating advanced intelligent systems.

We are interested in building intelligent systems that mimic human behavior. Let's study the key elements for bringing such systems to life.

Agents

An agent is a program or machine that can sense what's happening around it and make decisions to do something useful. It tries to achieve a goal by sensing its surroundings and then acting in a way that will get it closer to that goal. In other words, an agent can sense the environment using sensors and act accordingly through actuators.

The table below shows some interesting examples of agents with sensors and actuators.

Agent Type

Sensors

Actuators

Human

Eyes, ears, nose, skin, tongue

Hands, legs, mouth, vocal cords

Bird

Eyes, ears, beak, feathers

Wings, legs, beak

Robot

Cameras, infrared range finders, ultrasonic sensors, touch sensors

Motors, robotic arms, wheels

Autonomous vehicle

Radar, cameras, GPS, ultrasonic sensors

Steering mechanism, brakes, throttle control

Agent function

Agents receive input through sensors; we call this input "percept." A series of inputs perceived by an agent through its sensors is called percept history. Typically, an agent's decision on which action to take at any moment, using its actuators, can be based on the entire percept sequence up to that point. If we can define the agent's actions for every possible percept sequence, we have essentially described the agent's behavior completely. Mathematically, an agent's behavior is represented by the agent function, which maps each percept sequence to a corresponding action that the agent performs using its actuators.

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Example: Light control agent

Let's understand all these concepts with the aid of an example.

Environment

  • A room with a light that can be either on or off.

  • The room has a light sensor and a motion sensor.

Actions

  • Turn Light On

  • Turn Light Off

Sensors

  • Light Sensor (detects whether the light is on or off)

  • Motion Sensor (detects the presence or absence of a motion)

Percepts

  • A combination of light status (On/Off) and motion status (Detected/Not Detected). For example, (Light: Off, Motion: Detected).

Actuators

  • Mechanisms to control the light switch.

Here’s a simple table for our automated light control system:

Percept sequence

Action

[(Light: Off, Motion: Detected)]

Turn light on

[(Light: On, Motion: Not Detected)]

Turn light off

[(Light: Off, Motion: Not Detected)]

Do nothing

[(Light: On, Motion: Detected)]

Do nothing

As you add more percept variables or increase the number of possible values for each variable, the number of possible percept combinations grows exponentially, which in turn increases the complexity of defining the agent function. 

Mathematical representation:

Here is the agent function designed specifically for this scenario:

Given a percept p=(L,M)p = (L, M) ...